In recent years, white LEDs have been expected to be applied to illumination as the next-generation light sources instead of incandescent lamps or fluorescent lamps.
In an LED element for attaining wavelength-conversion by use of a phosphor, the light-emitting surface of its LED chip is molded with an organic binder resin containing a phosphor powder. When light rays emitted from the LED chip pass through this molded region, the light rays are wholly absorbed into the phosphor so that the wavelengths thereof are converted to different wavelengths, or the light rays are partially absorbed into the phosphor so that the converted light rays are combined with the transmitted light rays. In this way, desired light rays are emitted.
However, there remains a problem that the mold resin, which constitutes the LED element, is deteriorated by high-power light rays, which have short wavelengths in the range from blue wavelengths to ultraviolet ray wavelengths, so that the resin is discolored.
In order to solve the problem, in Patent Document 1, proposed is a phosphor composite member about which a material containing a lead-free glass powder having a softening point of 500° C. or higher and a phosphor powder is fired at a temperature not lower than the softening point of the glass to disperse the phosphor powder in the glass.
With the phosphor composite member disclosed in Patent Document 1, the phosphor powder is dispersed in the glass, which is an inorganic material; thus, it is possible to obtain a product which is chemically stable so as to be less deteriorated, and which is less discolored by light rays emitted therefrom.
Patent Document 1: Japanese Patent Application Laid-Open (JP-A) No. 2003-258308
Patent Document 2: JP-A No. 2005-11933